- DOCUMENT@0..52
    - WHITESPACE@0..1 " "
    - WHITESPACE@1..3 "\n\n"
    - INTERFACE_TYPE_EXTENSION@3..52
        - extend_KW@3..9 "extend"
        - WHITESPACE@9..10 " "
        - interface_KW@10..19 "interface"
        - WHITESPACE@19..20 " "
        - NAME@20..32
            - IDENT@20..31 "NamedEntity"
            - WHITESPACE@31..32 " "
        - FIELDS_DEFINITION@32..52
            - L_CURLY@32..33 "{"
            - WHITESPACE@33..38 "\n    "
            - FIELD_DEFINITION@38..51
                - NAME@38..42
                    - IDENT@38..42 "name"
                - COLON@42..43 ":"
                - WHITESPACE@43..44 " "
                - NAMED_TYPE@44..50
                    - NAME@44..50
                        - IDENT@44..50 "String"
                - WHITESPACE@50..51 "\n"
            - R_CURLY@51..52 "}"
- ERROR@0:6 "Invalid Type System Extension. This extension cannot be applied." extend
- ERROR@7:10 "expected definition" Cat
